package ArithMathOperation;
//*************************************************************************************
//    RationalNumber.java        Author:方艺雯
//
//    辅助机器进行运算，为书第七章的RationalNumber.
//*************************************************************************************
public class RationalNumber
{
        private int numerator, denominator;

        public RationalNumber(int numer, int denom)
        {
            if (denom == 0)
                denom = 1;

            if (denom < 0)
            {
                numer = numer * -1;
                denom = denom * -1;
            }

            numerator = numer;
            denominator = denom;
            reduce();
        }

        public int getNumerator()
        {
            return numerator;
        }

        public int getDenominator()
        {
            return denominator;
        }

        public RationalNumber reciprocal()
        {
            return new RationalNumber(denominator, numerator);
        }

        public RationalNumber add(RationalNumber op2)
        {
            int commonDenominator = denominator * op2.getDenominator();
            int numerator1 = numerator * op2.getDenominator();
            int numerator2 = op2.getNumerator() * denominator;
            int sum = numerator1 + numerator2;

            return new RationalNumber(sum, commonDenominator);
        }

        public RationalNumber subtract(RationalNumber op2)
        {
            int commonDenominator = denominator * op2.getDenominator();
            int numerator1 = numerator * op2.getDenominator();
            int numerator2 = op2.getNumerator() * denominator;
            int difference = numerator1 - numerator2;

            return new RationalNumber(difference,commonDenominator);
        }

        public RationalNumber multiply(RationalNumber op2)
        {
            int numer = numerator * op2.getNumerator();
            int denom = denominator * op2.getDenominator();

            return new RationalNumber(numer, denom);
        }

        public RationalNumber divide(RationalNumber op2)
        {
            return multiply(op2.reciprocal());
        }

        public boolean isLike(RationalNumber op2)
        {
            return (numerator == op2.getNumerator() &&
                    denominator == op2.getDenominator() );
        }

        public String toString()
        {
            String result;
            if (numerator == 0)
                result = "0";
            else
            if (denominator == 1)
                result = numerator + "";
            else
                result = numerator + "/" + denominator;
            return result;
        }

        private void reduce()
        {
            if (numerator != 0)
            {
                int common = gcd(Math.abs(numerator), denominator);

                numerator = numerator / common;
                denominator = denominator / common;
            }
        }

        private int gcd(int num1,int num2)
        {
            while (num1 != num2)
                if (num1 > num2)
                    num1 = num1 - num2;
                else
                    num2 = num2 - num1;

            return num1;
        }
        }

